Footings example 1 design of a square spread footing of a sevenstory building design and detail a typical square spread footing of a six bay by five bay sevenstory building, founded on stiff soil, supporting a 24 in. Diameter of mesh is approximately equal to the diameter of the slab. Unlike two way systems, where it is possible to design a floor. Following are the rcc slab design and detailing guidelines. Minimum thickness of beams and one way slabs values given in this table shall be used directly on members with normalweight concrete and grade 60 reinforcement. Slab may be supported on walls or beams or columns. Steel reinforcement calculation design of one way slab reinforced concrete encased steel beam floor slab beam reinforcement bar concrete coverslab hidden beam reinforcement cross section detailkuala lumpur malaysia june 2018 floor slab. These slabs are constructed to provide flat surfaces, usually horizontal, in building floors, roofs or other types of structures. Simply supported one way slab a rectangular reinforced concrete slab is simplysupported on two masonry walls 250 mm thick and 3. For continuous slabs, hogging reinforcements are provided at top over supports and bottom bars are curtailed. These materials are originally located at different websites.
Oneway and twoway slabs university of asia pacific. Detailing and design of earthquake resistant buildings made of reinforced concrete. But we will take in calculation the diameter of the mesh only. Reinforcement implementation, static and dynamic analysis. Simplified design of reinforced concrete buildings, fourth edition, 2011. Foreword the reinforced concrete design manual sp1711 is intended to provide guidance and assistance to professionals engaged in the design of castinplace reinforced concrete structures.
The objective function is the total cost of the slabs including the cost of the concrete and that of the reinforcing steel. The thickness of the slab has to be increased or the slab has to be shear reinforced. Design of reinforced concrete structures ii twoway slabs. With strength design method, the working dead load dl and live load ll are multiplied by. Beamless slabs beamless slabs are supported only on columns and are applied mostly in large industrial and. In flatplate floors, slab column connections are subjected to high shear stresses produced by the transfer of axial loads and bending moments between slab and columns. Can be used for larger spans with relatively higher cost and higher deflections one way joist system suitable span 6 to 9m with ll 46knm2. The quality of a completed floor slab is dependent on. Slab supported directly by columns are called flat slab. Ce 403, fall 20 one way slab design 3 4 aci 31811 referenced pp 2 4 rating.
Summary and comparison of twoway slab design results. The program covers wide range of two way slab systems and can be used for more complex slab layouts. The main reinforcement is arranged at the bottom of the slab that is usually described as the tension face. If slab is supported on all four sides and r shorter side longer side one way slab. Footings example 1 design of a square spread footing of a. We believe that the quickest way to learn is by actual application of the information.
Ce 433, fall 2006 slab design example 1 6 design a oneway slab for an exterior bay of a multistory office building using the information specified below. Two way slab is a slab supported by beams on all the four sides and the loads are carried by the supports along both directions, it is known as two way slab. Rectangular beams and oneway slabs page 5 of 9 maximum permissible steel ratio, max an overreinforced beam will fail in a brittle manner while an underreinforced beam will fail in a ductile manner. Slab design reading assignment chapter 9 of text and, chapter of aci31802 introduction aci318 code provides two design procedures for slab systems. The first reinforced concrete design manual formerly titled aci design handbook was developed in accordance with the design provisions of 1963 aci 318 building code by aci committee 340, design. The simplest routine structural element for illustration of design provisions in the code is the one way slab. In case of slabs thin members, no need of even minimum shear reinforcement.
A civil engineer must know all the aspects regarding the flat floor system. Pdf design calculation design of one way slab slab s1. One way slab reinforcement definition of one way slab. Beamless slabs beamless slabs are supported only on columns and are applied mostly in large industrial and public buildings. When a simply supported two way slab on four sides is loaded, the corners tend to curl and lift up. Assume partitions cannot be damaged by deflections. In two way slab, the ratio of longer span l to shorter span b is less than 2. Generally to design a reinforced concrete rc slab as a oneway spanning slab one. Steel bars have divided the whole area of slab in to many squares with side s.
Sometimes the minimum depth is adequate as per flexure design, but if deflection criteria arent fulfilled such slabs will face vibration even under small loads like walking, jumping, etc. Asce, secb course content slab on grades construction. For other conditions, the following modifications should be applied. D mm d 105 mm loads on slab self weight of slab 3. Design of concrete structures 14th edition, 2009, by arthur h. Define the term slab, one way slab, two way slab, shrinkage. The reinforcement diameter use in one way slabs will not exceed the 18 of the slab total depth.
Moduleiii design of short and long columns with axial and eccentric loading, design of isolated column footing. Slab shear strength twoway shear check the adequacy of slab thickness for punching shear twoway shear at an interior column figure 4. Rectangular beams and oneway slabs page 5 of 9 maximum permissible steel ratio, max an overreinforced beam will fail in a brittle manner while an underreinforced beam will. Slab is checked for deflection shear and development length. Member minimum thickness, h simply supported one end continuous both end continuous cantilever solid one way slab. The construction and design of concrete slabs on grade d. Pdf design of reinforced concrete slabs ninos dinkha.
In this example, the latter option will be used to achieve better understanding for the design of two way joist slab often called two way ribbed slab or waffle slab. Analysis and design of slabs one way civil engineers pk. In one way slab, as one side is larger as compared to the other one, the greatest load is carried by the larger side. Simply supported one way slab main reinforcement effective depth. Twoway joist concrete slab floor waffle slab system.
The pca computer program pcaslab can be used to expedite the design of different slab systems. Two way concrete slabs with openings the static system and the design of reinforcement. Twoway concrete slab on beams floor analysis and design. Determine moments at critical sections in each direction, normally the negative moments at supports and positive moment near midspan. Twoway concrete floor slab with beams design and detailing. Chapter 3 design of rectangular beams and oneway slabs. Twoway flat plate concrete floor system design structurepoint. May 02, 2017 two way slab is a slab supported by beams on all the four sides and the loads are carried by the supports along both directions, it is known as two way slab. Reinforced concrete, 2014, 9th edition, aci 31811 code edition, by jack c. Reinforcement detailing of reinforced concrete slabs. The rib reinforcement follows the same rules with the beam reinforcement. Application of one way slab provides useful flat surface one way slab may be used when there is architectural limitations it is the simplest form of slab design main reinforcement placing is one way, so there is a little congestion than two way slab 29. Oneway and twoway slabs oneway slabs transfer the imposed. One way slab reinforcement details daily civil engineering.
One way slab is supported by two parallel beams or walls. Reinforced concrete design 1 design of slab examples and. Thus, the maximum reinforcement ratio corresponds to a net tensile strain in the. Usually, when a slab is supported by a beam the support is.
Comparison of one way and two way slab behavior economic choices one way slab on beams suitable span 3 to 6m with ll 35knm2. Design of one way slab solved example of one way slab. Between the ribs, the slab is usually reinforced with a common wire mesh. Analysis of twoway slabs using direct design method shms. Plain slabs similar in shape to ground slabs take the load directly from the floor and transmit it to the beams. In this paper, one way and two way slabs with various end conditions are formulated as aci code. Distribute moments transverse at critical sections to column and middlestrip and if. Parameters include support conditions nine cases, span ratios lalb 0. Ce 403, fall 20 oneway slab design 3 4 aci 31811 referenced pp 2 4 rating. Flat slab analysis, design and detailing pdf civil. Slab is a common term used to describe the structural elements such as floors and roofs where the thickness of the element is very small compared to the length and. The ratio lb which is less than 2 is known as two way slab.
The following example illustrates the example building. Ce 433, fall 2006 slab design example 1 6 design a one way slab for an exterior bay of a multistory office building using the information specified below. One way slab reinforcement detail what is oneway slab. Dec, 2017 maximum of design reinforcement and minimum reinforcement requirements as per code is provided in both respective directions. A single slab with oneway reinforcement rebars will be analyzed with rcsolver. Design of slab examples and tutorials by sharifah maszura syed mohsin example 1. The output of the program for the slab in the example is shown in the following pages. Floor slabs can range from a simple residential basement slab to a heavyduty industrial floor.
Two way concrete floor slab with beams design and detailing design the slab system shown in figure 1 for an intermediate floor where the story height 12 ft, column crosssectional dimensions 18 in. For a simply supported two way slab a mesh reinforcement is provided to resist bending in both directions. This indirect, somewhat complex, method for determining the required amount of bonded reinforcement does not offer a direct comparison to the minimum reinforcement requirements for unbonded slabs specified in aci 31811, 3. Here, we have tried to gather various reading materials available in the web about flat slab floor system in one place. Analysis of two way ribbed and waffle slabs with hidden beams. Reinforcement detailing of a slab is done based on its support conditions. Minimum thickness of nonprestressed one way slab normal weight concrete and grade 60 grade 420 reinforcement. Behavior and reinforcement of one way slab the structural frame consists of four columns, two beams and one slab.
Finally, since shear reinforcement is not used in oneway slabs, the concrete must be able to resist the maximum shear force. What are the criteria for using aci moment coefficients for non pre. Mar 12, 2017 the direct design method is an approximate method used to analyze two way slabs. Shear reinforcement to check if shear reinforcement and which system can be used, one can calculate the minimal needed value of factor k sys. Chapter 3 design of rectangular beams and oneway slabs 12. The slabs having ratio of longer length to its shorter length l y l x greater than 2 is called one way slab otherwise as two way slab. Bending will take place in the two directions in a dishlike form. This paper presents an experimental and computational study on ribbed slabs with widebeam, two one way slabs and two two way slabs, with variable depths were tested to evaluate their resistance. Why is torsion reinforcement provided at edges of slabs. Twoway concrete slabs with openings the static system and the design of reinforcement. Difference between one way slab and two way slab system. Slab supported on two sides and bending takes place predominantly in one direction only is called one way slab. For example, the minimum slab thickness for a twohour fire rating is 4. Accordingly, main reinforcement is required in the two directions.
So, main reinforcement is provided in both direction for two way slabs. Limit state is actually the state of a structure, which does not fit into a suitable design criteria. Reinforced concrete slab level change detail reinforced. To demonstrate it, take an 8 12x11inch sheet of cardboard backing from a writing tablet and cut it to 8 12 inches square dont use corrugated p. Concrete slabs are commonly divided into the following types. Design of oneway slabs check if it is one way slab system if clear span in one direction, l1, is greater than or equal to two times the clear span in other direction, l2, then it is. There are some basic differences between one way slabs and two way slabs. Flat slab system is an important division of concrete floor system.
Minimum thickness of one way ribbed slabs summary of one way ribbed slab design procedure. Oneway slabs transfer the imposed loads in one direction only. In the design of twoway reinforced concrete slabs, e. Pdf the paper presents the cost optimization of reinforced concrete simply supported. This second edition of limit state design of reinforced concrete is updated according to is 456. The ratio of the total costs was found to be within the range 1. Reference 5 focused on analysis of two way ribbed slabs with. Reinforced concrete design 1 design of slab examples.
In two way slabs, load will be carried in both the directions. Find the following parameters for design moments in step 2 per unit width step 4 note. Suppose there is a circular slab having steel in mesh form within diameter d. Our friend mohit sharma has already highlighted the essentials for a one way slab. If a beam is underreinforced and the ultimate load is approached, the steel will begin to. Would love to provide these pictures for better clarity of the viewers. This paper presents a cuckoo optimization algorithm coa model for the cost optimization of the one way and two way reinforced concrete rc slabs according to aci code. They may be supported on two opposite sides only fig.
Civilax is the knowledge base covering all disciplines in civil engineering. Rectangular beams and one way slabs page 3 of 9 design of rectangular beams and one way slabs continued a. It is independent of the loading, service stresses, and span length. Ce 433, summer 20 slab design example 1 5 design a one. Slabs having supports on less than four sides can be designed as one way. Minimum depth of the one way concrete slab, most of the times is governed by deflection criteria. Pdf cost optimum design of reinforced concrete simply.
Shear due to loads always must be less than the shear strength of concrete. Jan 05, 2018 what is one way slab what are the reinforcement in one way slab give the example of one way slab search more video in this youtube channel for civil site wor. Difference between one way slab and two way slab simple. Deep ribs, the concrete and steel quantities are relative low expensive formwork expected. If none of the values satisfies, you need to change d. Design of one way and two way slabs, design of staircases. Aug 17, 2017 for the love of physics walter lewin may 16, 2011 duration.
The construction and design of concrete slabs on grade. Nonprestressed bonded reinforcement in posttensioned. Step 2 design forces draw panel of slab and indicate maximum design moments, shears and in plane loads, if any, per unit width of slab. Simplified design of reinforced concrete buildings, fourth edition, 2011 mahmoud e. One way and two way slabs one way slabs transfer the imposed loads in one direction only. A fundamental task in the design of reinforced concrete structures is to. Determine the allowable unform live load that a one way slab can sustain 3. Introduction concrete slabs on grade are a very common type of concrete construction. A one way slab is defined for purposes of this book as a flexural member with depth small relative to other dimensions, supporting gravity loads applied normal to and directly over its surface, spanning in one direction between parallel supports, and reinforced for flexure.
Oneway slab design spreadsheet civil engineering community. Define the term slab, one way slab, two way slab, shrinkage and temperature reinforcement, main reinforcement. Design procedure steps for one way slab slab design steps. Finally, since shear reinforcement is not used in one way slabs, the concrete must be able to resist the maximum shear force. Reinforced concrete slab design and detailing guidelines for depth of slab, loads on slab, reinforcement guide for one way and two way slabs as per is 456. Learn to design reinforced concrete one way slabs through. To clear the concept of one way and two way slabs a table is shown below. Calculate the design moment strength of a one way slab 2. Two way slabs are normally supported from four sides.
The bottom of the footing is ft below finished grade. The basic design procedure of a two way slab system has five steps. C limit state design is a method incorporated in structural engineering. One way solid slabs are designed as rectangular sections subjected to shear and moment. Concrete slabs come in a variety of forms depending on their locations. Plan view of floor system assume partitions will not be damaged by deflections. The structural action of a oneway slab may be visualized in terms of the. Design of reinforced concrete structures ii two way slabs 1 1. Reinforced concrete slab design and detailing guide is456. In one way slab main reinforcement is parallel to shorter direction and the reinforcement parallel to longer direction is called distribution steel. Consequently, the main reinforcement is necessary to withstand the moments produced and designed for the same. Once design compressive strength of concrete and yield stress of reinforcement are specified, the next steps are followed.
For one way slab, main reinforcement is computed by a formula in limit state design that is determined by comparing compressive force as well as tensile forces. One way spanning slabs should be treated as beams of unit width and chapter 2 should be followed except for minimum shear reinforcement. Unlike two way systems, where it is possible to design. The slab has to carry a distributed permanent action of 1. However, mainly as far as the stirrups are concerned, the amount of placed rebars is not as large as it is in beams. To study the flexural behaviors of the concrete shear walls with precast hollow slab, one cast insitu reinforced concrete shear wall and two precast two way hollow slab shear walls. To attempt to make sure that only ductile failures can occur the aci code limits the maximum steel ratio as following. The availability of a scripting interface within a given software is a sine qua none.
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